Abu Omar al-Baghdadi, self-styled head of the al-Qaida front group the Islamic State of Iraq, said in a speech posted on an extremist Web site that it would be better "for you and us" to "withdraw your forces," according to the SITE Intelligence Group that monitors militant Web sites.
"You do not interfere in the affairs of our countries," he continued in an apparent reference to Muslim dominated nations. "We, in turn, will not prevent commerce with you, whether it is in oil or otherwise."
Al-Baghdadi blamed the global financial crisis on the wars "launched in Muslim countries" and said he was issuing the call on behalf of "my brothers in Iraq, Afghanistan, Somalia, and Chechnya," SITE said.
The U.S. military says al-Baghdadi is an actor who provides a voice for al-Qaida in Iraq propaganda.
In a separate statement, the Mujahedeen Army, a Sunni insurgent group, urged Obama to withdraw U.S. troops from Iraq or face "days that will be more difficult than the nightmare experienced by his predecessor."
According to SITE, the statement said both Democrats and Republicans share attitudes hostile to Muslims.
The authenticity of the statements couldn't be verified.
Obama has called for an increase in forces in Afghanistan and a withdraw of combat troops from Iraq in 16 months, but said that the time period wasn't rigid and could be adjusted.
The Islamic State of Iraq purports to be an umbrella organization of religious extremist groups including al-Qaida in Iraq. The Mujahedeen Army emerged in late 2004 and has distanced itself from al-Qaida because of opposition to the terror movement's attacks on Shiite civilians.
The U.S. military says U.S. and Iraqi forces have killed a senior al-Qaida-in-Iraq leader. A statement says Abu Ghazwan commanded insurgent cells and was responsible for building car bombs and training suicide bombers.
